Air and fallout. Gross beta activity in airborne particulates and precipitation.
D000398:Air Pollution, Radioactive; D002489:Central America; D049673:History, 20th Century; D066298:In Vitro Techniques; D009656:North America; D011834:Radiation Monitoring; D011847:Radioactive Fallout; D013020:South America
D011847:Radioactive Fallout